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MEMS@DAC 2010: Ready to Cross the Chasm?

By Jim Hogan
Ten years ago the Design Automation Conference (DAC) may have seemed like an odd place for a discussion on mechanical design, or even MEMS – micro-electronic mechanical systems. In the eyes of many IC designers, it was still a technical curiosity. Anyone at the 2010 DAC toting the newest mobile products from Apple – which was a large percentage of DAC crowd this year – can attest to the power of MEMS, and more importantly their increasing presence in the traditional world of IC design.

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ISuppli predicts that unit shipments of MEMS gyroscopes will ramp up from zero in 2009 to 285 million in 2014.

“The maker of the MEMS gyro used in the iPhone 4 is not yet known, since the device does not become available until June 24 and Apple does not reveal the identity of its suppliers. STMicrosystems, Invensense and Analog Devices are all marketing MEMS gyroscopes suitable for mobile handsets, but iSuppli guesses that Apple is using STMicro’s three-axis gyro, since the company is already the supplier of the MEMS accelerometers used in Apple’s current iPhone 3GS, iPad and iPod Touch.”

Long pigeon-holed in the steady, albeit somewhat slow-moving, domains of ink jet printers, DLP mirrors and automotive air bags, MEMS have begun to emerge as powerful differentiators for any type of product that needs to interact with or sense the outside world. See the Nintendo Wii or Apple’s ubiquitous rotating- displays to understand how MEMS can help satisfy a virtually insatiable consumer demand for cool new functionality where physical intelligence enhances the user experience.

So there we were at DAC in Anaheim, talking MEMS at a Birds of a Feather meeting entitled “MEMS@DAC: Ready to Cross the Chasm” (maybe next year MEMS will have arrived to the point where the topic will get a seat at a real conference session). There were folks from MEMS design tool companies, traditional EDA supplies, commercial foundries and a few other people with a genuine interest in what’s next for MEMS.

It’s actually a bit surprising that there weren’t more people at the session (the somewhat inconvenient meeting time at 6:30 p.m. between the show hours and the after parties notwithstanding) – the MEMS market is predicted to grow by more than 40 percent from 2008 to 2012, from just over $7 billion worldwide to over $13 billion, according to market research firm Yole Development. The growth is almost entirely fueled by consumer applications, as well as the emerging area of energy harvesting – both areas where MEMS capabilities can enable significant innovation. People may wonder a bit on the application, but if you look just at wireless communication and the potential for local advertising that MEMS enables, my guess it will actually grow faster than the Yole suggests.

Two different worlds: MEMS and IC Design
My personal feeling, having been around the IC design industry for 30-plus years, is that we are all a bit mystified and amazed, if not intimidated, by MEMS. Although almost all MEMS devices are tightly integrated with electronics, either on a common silicon substrate or in the same package, MEMS design has traditionally been separated or discrete from IC design and verification.

There are a number of reasons for this:

  1. MEMS design proceeds hand-in-hand with refinements to the MEMS fabrication process, unlike IC design which relies on standardized CMOS processes; the result is up unto recently the realm of Ph.D.’s in mechanical engineering and material science.
  2. MEMS, in contrast to ICs, are fundamentally three dimensional (3D), allowing an extra degree of freedom in design that translates into a much larger available design space. It also has additional forces to deal with, such as displacement.
  3. MEMS rely on coupled multi-physics effects to function. In particular, many MEMS designs rely on complex coupling between highly non-linear electrostatic forces and mechanical structures. Or, for instance, high-frequency MEMS resonators for RF applications rely on complicated high-frequency resonances in piezo-electric materials.
  4. MEMS devices are almost always tightly integrated with analog/mixed-signal ICs for sensory control, either on a common silicon substrate or in the same package.

Eventually the MEMS design must be handed off to an IC design team in order to go to fabrication, but the handoff typically follows an ad-hoc approach that requires a lot of design re-entry and expert handcrafting of SPICE-like behavioral models for functional verification. The present approach to MEMS design, with separate design tools and ad-hoc methods for transferring MEMS designs to IC design and verification tools, is simply not up to the requirements of developing products for consumer markets. New approaches are necessary to enhance MEMS design and bring it into the IC design mainstream, so design costs are reduced, time-to-market is shortened, and MEMS design is no longer confined to teams of specialists inside IDMs. This will create the democratization of MEMS design and manufacture, thus taking it out of the realm of Ph.Ds and moving it into the hands of practitioners, not just researchers.

A critical key to accomplishing this “democratization” is to build an integrated design flow for MEMS devices and the electronic circuits they interact with, using a structured design approach that avoids manual handoffs. At DAC we saw that there was progress being made in terms of tearing down the walls between IC design and MEMs development by companies like Coventor, Cadence and The MathWorks.

Helping MEMS “Cross the Chasm”
With tool flows starting to hit the market from companies like Coventor, the next priority is support from pure-play foundries. MEMS historically require specialized process development for each design, resulting in a situation often described as “one process, one product.” While there are a number of specialized MEMS foundries, support from pure-play foundries like TSMC has been very limited. Thus, most successful MEMS products on the market today were designed by teams of experts inside IDMs who have their own process technology. A foundry ecosystem with reference flows, foundational silicon IP libraries, and process design kits is needed.

When such an ecosystem finally becomes available—and it is starting—electronic systems developers can finally break free from the “one process, one product” tradition and MEMS design will become more accessible to fabless companies. Furthermore, MEMS will generate income for the foundries and drive some business to the mature process nodes that MEMS is likely to involve.

MEMS devices offer great potential for continuing the pace of miniaturization that began with Moore’s Law. We’ll see more than Moore as designers explore the 3D space. MEMS already has enabled great advances, from safer cars to digital projection, and these chips increasingly are revolutionizing the way we interface with the latest multi-function consumer electronics. But MEMS design has for too long been confined to specialists who use an ad-hoc design methodology with little or no connection to the electronic design environment.

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